This study examined the effect of social network descriptive sexual norms and behaviors on the sexual behaviors of people who inject drugs (PWID). Data from HPTN037 of 232 PWID (egos) and 464 network members (alters) were used in multilevel multivariate logistic regression models. Egos whose alters reported multiple sex partners had greater odds of multiple sex partners (aOR 2.20, 1.13-4.29). Egos' norms of condomless sex with primary (aOR 2.67, 1.15-6.17) and casual (aOR 2.38, 1.01-5.59) partners and egos' norms of giving (aOR 5.52, 1.87-16.25) and receiving (aOR 7.38, 1.34-40.66) money/drugs for sex were associated with the egos' respective behaviors. History of sex between an ego and alter was not associated with increased influence of alters' norms and behaviors on egos' sexual behavior. Findings provide support for developing interventions that target descriptive norms and selective network behavioral characteristics to decrease sexual HIV risk behavior among PWID.